Prefabricated tower foundation comprising equipment shelters and a method for its deployment on site

ABSTRACT

A foundation for a tower of a telecommunication site or the like, which may serve a plurality of networks or users and requires therefore a plurality of equipment shelters, is basically formed of a plurality of prefabricated concrete equipment shelters coupled altogether so as to function as a monolithic foundation. When an increase of the foundation&#39;s overturning resistance capacity is required, an enhancement assembly of prefabricated foundation elements coupled altogether by similar means to those used for coupling said shelters, is placed under said basic assembly of shelters, and the two assemblies are mechanically vertically fastened to each other.

FIELD OF THE INVENTION

The present invention relates in general to foundations for towers and,in particular, to foundations for towers in telecommunication sites thatare commonly used by a plurality of networks or users, each network oruser requiring its own equipment shelter.

BACKGROUND OF THE INVENTION

Many types of wireless telecom networks, and especially cellulartelephone networks or the like, require a large number of remote,unmanned sites.

In areas where no buildings, or only very low-rise buildings exist, suchsites are normally located on bare ground, and are usually referred toas “Greenfield Sites”. A Greenfield site employs a tower which supportsvarious antennae at required heights above the ground, and in most casesalso at least one shelter, which is usually a prefabricated small roomserving as an enclosure for the indoor electronic equipment. When theGreenfield site serves more than one network, either a plurality ofshelters or a single larger shelter may be used. In such shared sites,the facility of housing each network's equipment in a separatelyaccessible individual room contemplates an operational and securityadvantage, as each operator may independently maintain and exercise itsown access control procedures.

The construction of a new Greenfield site in compliance with the lawrequires, in most if not all countries, the prior obtainment of abuilding permit.

In recent years, as the number of various network operators in eachcountry, and consequently the number and density of Greenfield sites,have been constantly increasing—the obtainment of building permits fornew Greenfield sites serving a single network has become increasinglydifficult, especially in the more developed countries, whereenvironmental aspects have become an increasingly importantconsideration. The authorities tend to encourage network operators toshare amongst themselves the use of common new sites, and at the sametime to build sites which present minimal possible disturbance to theenvironment, by making (amongst others measures) most efficient use ofground space.

At the same time, new wireless telecom networks tend increasingly to bebuilt under fast roll-out constraints. Consequently, solutions whichemploy prefabricated elements instead of cast-on-site concrete elements,thus enabling more rapid construction in almost any weather condition,contemplate clear advantages to network roll-out managers.

An additional important aspect is the budgetary one: in the vastmajority of Greenfield sites built to date, or even those beingpresently built, the tower foundation and the equipment shelter (orshelters) are function-wise totally separated from each other. Asolution which makes a multi-functional use of the same elements (i.e.the shelters) has therefore the potential of significant cost savings,compared to the “conventional” solutions described above.

Accordingly, there is a felt need for, and an expected welcomingacceptance of, a rapidly deployable foundation for the tower inGreenfield telecom sites serving a plurality of networks or users,comprising a plurality of prefabricated concrete equipment shelterscoupled together, thus forming a suitable foundation for the tower, andaltogether consuming minimal ground-space.

PRIOR ART PUBLICATIONS

Numerous patents, patent applications and other prior art publicationsrelate to antenna towers or the like, foundations for the same, and toequipment shelters or other type enclosures for electronic equipment,meant to be located near the base of a tower.

The following publications are believed to be the most relevant forereference as prior art herein:

Disclosed in International Patent Application No. PCT/BR98/00029 toBITTENCOURT DE MIRA is a shelter for telecommunications equipment,particularly suitable for housing equipment utilized in cell phonesystems and other telecommunications systems, this shelter beingpositioned in the internal region of a telecommunications tower, andhaving a cross section analogous to that of the tower. In addition, theshelter is divided into at least two floors. There is also disclosed atelecommunications tower, particularly utilizable in cell phone systems,which comprises a shelter positioned in its internal region.

Disclosed in International Patent Application No. PCT/GBOO/04846 toSMITH is a foundation comprising at least one prefabricated foundationelement.

Disclosed in International Patent Application No. PCT/IL01/00174 toSILBER is a foundation for a tower, which is formed of a plurality ofprefabricated slabs coupled together so as to function as a monolithicfoundation.

Disclosed in U.S. Pat. No. 6,351,250 to GILLEN is an antenna tower andsupport apparatus, which includes a foundation and a building mounted onthe foundation, the building including a plurality of vertically spacedapart building sections (preferably two, three or more), a bottom and atop. A tower is supported upon the top of the building. A plurality ofantenna are attached at multiple elevational positions. Each buildingsection has a security area that is separate from the security area ofthe other building sections. A plurality of antenna portals are providedat least one on each building section. A plurality of antenna cables areprovided, each cable extending from an antenna to a security area of abuilding section via an antenna portal, wherein each security area hasat least one antenna cable that extends to it. Each security area hastelecommunications equipment that is connected to one of the antennacables.

Disclosed in U.S. Patent Application Publication No. 2002/0023394 toMcGINNIS is an easily-constructed foundation for an antenna supporttower, that requires no fabricated support surface at the installationsite. The foundation is a radial array of prefabricated buildingsconnected near their inner corners to each other. In a first embodiment,one leg of a multi-legged tower rests on each building, the buildingstransferring forces from the tower to the support surface below thebuildings. In a second embodiment, a tapered monopole tower is locatedin the center of the array of buildings. The monopole tower may rest ona prepared surface or may be supported above the support surface.Support structures, each having a central ring and radially extendingarms, are attached at the building connection points, one supportstructure above the other. The monopole tower is positioned within thecentral ring, transferring lateral loads through the ring and arms tothe buildings, negating the need for a moment base.

The shelter to BITTENCOURT DE MIRA is indeed designed to facilitatespace-efficient installation of a telecommunication site, but it has norole whatsoever as a foundation to the tower or any other structuralrole.

The foundation to SMITH may indeed consist of a plurality ofprefabricated foundation elements, but these elements are all rathersmall, and designed to support altogether not more than one equipmentshelter.

The foundation to SILBER indeed comprises a plurality of prefabricatedconcrete elements, but these elements are flat slabs, and the connectionthere between is made substantially vertically, whereas the connectionbetween the prefabricated shelters in the present invention is madesubstantially horizontally. Furthermore, there is no mention whatsoeverto equipment shelters.

The antenna tower and support apparatus to GILLEN is employingvertically spaced apart building sections (i.e. shelters) while in thepresent invention the equipment shelters are spaced apart horizontally.Furthermore, the antenna tower and support apparatus to GILLEN require aseparate, conventionally built foundation, while in the presentinvention the coupled shelters themselves serve essentially also as afoundation for the tower.

The foundation to McGINNIS is indeed the publication which is atshortest distance to the present invention, as there is also a pluralityof equipment shelters spaced apart horizontally, connected altogetherand suited to serve as a foundation for a tower. Nevertheless, thesystem used in the present invention for coupling every two adjacentshelters is totally different than that disclosed by McGINNIS, not onlyin detail but in the essential basic concept: in the foundation toMcGINNIS the shelters are connected to each other only in their corners,while in the present invention the shelters abut each other, and arecoupled to each other, through substantial wall surfaces. This providesa much stronger structural bonding between the shelters, and indeedfacilitates their functioning altogether as a monolithic foundation.Furthermore, McGINNIS envisions only radially symmetrical layouts ofsubstantially rectangular identical shelters, which therefore cancontact each other only at their inner corners, while the presentinvention envisions numerous possible layouts of various shape shelters,either symmetrical or un-symmetrical. Even when utilizing four identicalrectangular shelters according to the present invention, these shelterswould not be arranged radially, but rather in a much more compactarrangement, as disclosed in the preferred embodiment herein. Owing tothe said layout advantage, the foundation constructed according to thepresent invention would consume a much smaller ground space than asimilar foundation constructed according to McGINNIS, and will also havea much neater appearance: a smooth square plan contour instead of across-like plan contour. Finally, the present invention also features anoptional foundation enhancement possibility, which is not envisioned atall by McGINNIS.

SUMMARY OF THE INVENTION

It is an aim of the present invention to provide an efficient overallsolution for a telecommunication site or the like, based on the groundand employing a tower, which is utilized by a plurality of networks orusers. The efficiency of the solution provided by the present inventionresults from its basic concept, of making a multi-functional use of aplurality of prefabricated concrete equipment shelters.

There is provided, therefore, in accordance with a preferred embodimentof the present invention, a foundation for a tower, comprising aplurality of prefabricated concrete shelters, each suitable for housingindoor equipment of a telecom network or the like, said shelters beingarranged on site such that every shelter is abutting and coupled to atleast one other adjacent shelter, such that a substantially verticalsurface of contact exists there between, across which the means of saidcoupling is transversely effected, resultantly all said shelters aremechanically attached together and function as a monolithic foundation.

According to another preferred embodiment of the present invention, eachof said shelters includes certain apparatus for anchoring part oftower-base, located on its roof, such that said anchoring apparatus ofthe entirely assembled foundation is geometrically fit and mechanicallyadequate to receive the base of said tower, either directly or throughan interfacing tower-base structure.

There is also provided, in accordance with a preferred embodiment of thepresent invention, a method for constructing a foundation for a tower,said method primarily including:

-   -   Preparing the prefabricated components of said foundation, as        described above;    -   Executing site preparation works in designated site area, so as        to form a planar and horizontal adequate support surface for the        foundation, moderately higher than the surrounding ground level;    -   Placing said prefabricated concrete shelters in their final        designated positions in a sequential order, and effecting and        tightening said means of transversely coupling the shelters in        the same sequential order.

In order to facilitate utilization of the present invention even whenthe overturning loads effected by the tower, due to its height andwind-drag exposure, exceed the overturning resistance capacity of thebasic foundation assembly of shelters, there is further provided, inaccordance with an alternative embodiment of the present invention, afoundation enhancement assembly, placed underneath the assembly of saidshelters, the two assemblies being fastened to each other by appropriatemeans of vertical fastening, said foundation enhancement assemblycomprising.

A plurality of equi-high prefabricated concrete foundation elements,each having the shape of a box open at its top, said foundation elementsbeing arranged on site such that every foundation element is abuttingand coupled to at least one other adjacent foundation element, such thata substantially vertical surface of contact exists there between, acrosswhich the means of said coupling is transversely effected, resultantlyall said foundation elements are mechanically attached together andfunction as a monolithic foundation.

According to yet another preferred embodiment of the present invention,said foundation enhancement assembly further includes an outwardlyhorizontal projection of its floor from its perimeter walls, all alongits perimeter or along any part thereof, so as to increase the contactarea between the bottom surface of said foundation enhancement assemblyand the underlying supporting surface.

There is also provided, in accordance with another embodiment of thepresent invention, which may be effected in conjunction with theutilization of said foundation enhancement assembly, a method forconstructing said foundation, including:

-   -   Preparing the prefabricated components of said foundation,        including said shelters and said foundation elements, as        described above;    -   Executing site preparation works in designated site area,        including excavation, so as to form a planar and horizontal        adequate support surface for the foundation, at a depth below        the surrounding ground level substantially equal to the height        of said foundation enhancement assembly;    -   Placing said prefabricated foundation elements in their final        designated positions in a sequential order, and effecting and        tightening said means of transversely coupling the foundation        elements in the same sequential order;    -   Backfilling and compacting the excavation around the placed and        coupled foundation elements, preferably in individual layers;    -   Filling up the entire capacity within each of said foundation        elements, as well as (if applicable) of the cavity encircled        thereby, with local soil or with imported soil or granular        material or sand;    -   Placing said prefabricated shelters in their final designated        positions on top of said foundation elements in a sequential        order, effecting and tightening said means of transversely        coupling the shelters to each other, and effecting and        tightening said means of vertical fastening said shelters to        said foundation elements, all in the same sequential order.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention, as well as some preferred embodiments thereof,may be best understood and appreciated from the following detaileddescription made in conjunction with the drawings in which:

FIG. 1 is a schematic isometric view of a tower mounted on a foundationconstructed in accordance with one embodiment of the present invention;

FIG. 2 is a schematic top view of the tower and foundation of FIG. 1;

FIG. 3 is a horizontal cross sectional view of the entire foundation ofFIG. 1;

FIG. 4 is a vertical cross sectional view of the entire foundation ofFIG. 1, made through its central vertical axis;

FIG. 5 is another vertical cross sectional view of the entire foundationof FIG. 1, made closer to one of its edges;

FIG. 6 is a side view of a wall of a shelter constructed in accordancewith the embodiment illustrated in FIGS. 1 to 5, which is designed toabut an adjacent shelter's wall;

FIG. 7 is a cross sectional view of two abutting walls of adjacentshelters constructed in accordance with the embodiment illustrated inFIGS. 1 to 6;

FIG. 8 is a local cross-sectional view of two abutting walls of adjacentshelters, illustrating one embodiment of the means for coupling said twoabutting walls;

FIG. 9 is a local cross-sectional view of two abutting walls of adjacentshelters, illustrating an alternative embodiment of the means forcoupling said two abutting walls;

FIG. 10 is a local cross-sectional view of two abutting walls ofadjacent shelters, illustrating two additional alternative embodimentsof the means for coupling said two abutting walls, differing veryslightly from each other, both contemplating certain advantages over theembodiments illustrated in FIGS. 8 and 9;

FIG. 11 is a schematic top view of a foundation constructed inaccordance with an alternative embodiment of the present invention,utilizing four shelters, each differing in its shape from all theothers;

FIG. 12 is a schematic top view of a foundation constructed inaccordance with yet another alternative embodiment of the presentinvention, utilizing three identical shelters, having an overallcircular contour shape and a central vertical shaft of a triangularcross section;

FIG. 13 is a schematic top view of a foundation constructed inaccordance with yet another alternative embodiment of the presentinvention, utilizing four identical shelters, having an overall squarecontour shape and a central vertical shaft of a square cross section;

FIG. 14 is a schematic top view of a foundation constructed inaccordance with yet another alternative embodiment of the presentinvention, utilizing six identical shelters, having an overall hexagonalcontour shape and a central vertical shaft of a hexagonal cross section;

FIG. 15 is a schematic top view of a foundation constructed inaccordance with yet another alternative embodiment of the presentinvention, utilizing four identical shelters, having an overall squarecontour shape and no internal vertical shaft at all;

FIG. 16 is a schematic top view of a foundation constructed inaccordance with yet another alternative embodiment of the presentinvention, utilizing three shelters, having an overall rectangularcontour shape and no internal vertical shaft as well;

FIG. 17 is a schematic isometric view of a foundation enhancementassembly constructed in accordance with one embodiment of the presentinvention, which is suitable for enhancing the foundation assemblyillustrated in FIGS. 1 to 7;

FIG. 18 is a schematic isometric view of one of the four foundationelements forming the a foundation enhancement assembly illustrated inFIG. 17;

FIG. 19 is a schematic top view of the floor of one of the sheltersillustrated in FIGS. 1 to 7, further adapted so as to be verticallyfastened to one of the foundation elements illustrated in FIGS. 17 and18;

FIG. 20 is a local cross-sectional view of two abutting walls ofadjacent foundation elements, as well as the two abutting walls of theadjacent shelters supported by said foundation elements, illustratinggenerally also the means for vertical fastening between the shelters andthe foundation elements;

FIG. 21 is an enlarged cross-sectional view of one embodiment of themeans for vertical fastening between the shelters and the foundationelements;

FIG. 22 is a series of schematic isometric views of the various steps inone embodiment of the method for constructing the foundation illustratedin FIGS. 1 to 7;

FIG. 23 is a series of schematic isometric views of the various steps inone embodiment of the method for constructing the foundation enhancementassembly illustrated in FIG. 17, and on top of it the foundationassembly illustrated in FIGS. 1 to 7.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a multi-functional foundation for thetower of a telecommunication site or the like, where the design of aplurality of prefabricated concrete equipment shelters, which arerequired primarily for the purpose of housing the indoor equipments of aplurality of networks utilizing said tower, is made such that theseshelters, after being appropriately positioned and coupled altogether,function also as a suitable foundation for the tower.

As long as the overturning resistance capacity (by structural analysismethods complying with all applicable standards) of the basic foundationassembly described above is found sufficient to stabilize said tower,considering its height and antenna loading—said basic foundationconstruction, comprising only said coupled shelters, will be applied,and will therefore be placed totally above ground level. Nevertheless,even in said case, the natural soil underneath the foundation (with someexcess dimensions there around) down to a certain depth, all subject toengineering choices or constraints, may be replaced with an improvedquality soil or base material, such as gravel, crushed stone or sand,which would be properly compacted before the foundation assembly workscommence.

When, however, considering the tower's height and antenna loading, theoverturning resistance capacity of the basic foundation assembly(described in the previous paragraph) is not sufficient and must beincreased—an enhancement assembly of prefabricated foundation elements,which are coupled together in a method similar to that used for couplingtogether said shelters, and which is placed under said assembly ofcoupled shelters (and, in most part, under finished ground level) comesinto use. The assembly of coupled shelters is mechanically fastened downto said enhancement assembly of prefabricated foundation elements usingan adequate fastening method. It would be appreciated by any personskilled in the art, after studying the details of the foundationenhancement as described herein, that the complete enhanced foundationassembly has a considerably increased overturning resistance capacity,compared with the basic foundation assembly described in the previousparagraph.

Thus, one purpose of the present invention is to provide a neat andefficient solution for the tower foundation and equipment housing insites where the tower is utilized by a plurality of networks or users,and therefore a plurality of equipment shelters is required. Aby-product of the present invention, resulting from the essence of thesolution, is that the tower base, located on the shelters' roofs, is notaccessible to un-authorized visitors, removing the basic need tosurround the site with a fence.

The efficiency of a site utilizing the present invention may bemeasured, most meaningfully, in terms of its lower cost, compared to thealternative aggregate cost of a plurality of other type shelters,together with the cost of a conventional cast-on-site foundation for thetower, and a fencing all around. Additionally, said efficiency may bemeasured in terms of the much smaller ground-area required for amulti-user site (i.e. a site used by a plurality of users or networks),a ground area saving which is desirable for both increasing thefeasibility of site lease and permitting, and at the same time reducingland lease costs for the long term.

The other purpose of the present invention is to provide a rapidlyexecutable solution for such multi-user Greenfield sites, a propertywhich may be highly appreciated and most welcome when the sites need tobe built under fast network roll-out constraints. The entire foundationis made of completely prefabricated components, having transportabledimensions and weights, and except for a possible thin layer of lean (ornormal) concrete, which has no structural significance, no othercast-on-site concrete is required in order to form a monolithic andstable foundation for the tower.

The foundation according to the present invention is formed of aplurality of prefabricated concrete components, which may be allidentical or, alternatively, may comprise several types. The heart ofthe invention is the geometrical arrangement of all said components, ofwhich the exact shape and dimensions of each are determined, as well asthe methods used to couple together all the components of thefoundation, and make them function effectively and safely as if theywere one monolithic foundation.

It would be appreciated by persons skilled in the art that a foundationconstructed according to the present invention, while being sound forthe long term and therefore suitable to serve as a permanent facility,is also removable if needed, without leaving a non-recoverable trace onsite, and therefore may also be suitable for temporary applications.Besides the positive aspect of cost recovery, when the intension isindeed to deploy a short or medium term solution, there is, in somecountries, an additional advantage associated with said “removable”feature: a simplified Building Permit procedure.

Referring to FIGS. 1 and 2, there are shown respective isometric andplan views of a tower foundation and a tower constructed in accordancewith one embodiment of the present invention. As can be seen, a tower 20is mounted on a foundation 10. Tower 20 can be any possible type oftelecommunication tower (or other purpose tower) requiring a soundfoundation to sustain its loads and stabilize it against overturning.Tower 20 can be of various conventionally known shapes (i.e. LatticeTower or Monopole type), heights, or dimensions. The tower illustratedin FIGS. 1 and 2 is a Lattice Tower with four legs 22. The bottom endsof legs 22 are provided with base plates 24, which are a commonly usedmeans for providing adequate structural connection between the tower 20and the foundation 10, as described below. Other possible alternativemeans for providing said adequate structural connection are also knownin the art.

The tower foundation according to the present invention is formed ofseveral prefabricated equipment shelters, preferably at least threeshelters, made of reinforced concrete. In the embodiment of theinvention illustrated in FIGS. 1 and 2, the foundation 10 comprises fouridentical equipment shelters 12. Each of the equipment shelters 12 inthis embodiment is of a substantially rectangular plan contour, and isprovided with a door opening 14 on one of its outer walls. The entirefoundation assembly 10 is of a substantially square plan contour.

Shelters 12 are arranged such that a polar symmetry exists therebetween, about a central vertical axis of polar symmetry 1. In thepreferred embodiment illustrated in FIGS. 1 and 2, tower 20 is alsoconcentric with said central vertical axis of polar symmetry 1.

Every two adjacent shelters 12 are abutting each other, with asubstantially vertical surface of contact 50 defined there between. Themeans for coupling together said every two adjacent shelters 12, asdescribed below, are effected transversely through said surface ofcontact 50, or more accurately, through both abutting concrete walls,each located on either side of said surface of contact 50.

It will be appreciated that the equipment shelters made according to thepresent invention may be all identical in plan shape and dimensions, orall different from each other, or part of them identical and the restdifferent, all depending on engineering choices or constraints. However,all said equipment shelters must geometrically fit each other such thataltogether, when positioned and coupled as designed for that purpose,they form a complete foundation of the designed shape and size. FIG. 11illustrates an embodiment of the invention where a complete foundationassembly 11 of a substantially square plan contour is made-up by fourshelters 15, 16, 17 and 18, where none of said shelters is identical toany of the other shelters.

It will be further appreciated that the contour shape (and size) of thecomplete foundation assembly made according to the present invention maybe of various geometrical shapes, such as substantially triangular,square, hexagonal, circular, etc.

Referring now to FIG. 12, there is shown a substantially circularfoundation assembly 31, made-up of three identical equipment shelters32. FIG. 13 illustrates a substantially square foundation assembly 33,made-up of four identical equipment shelters 34, shaped according to adifferent embodiment of the present invention than that illustrated inFIGS. 1 and 2. FIG. 14 illustrates a substantially hexagonal foundationassembly 35, made-up of six identical equipment shelters 36. In allthese cases, when the shelters are all tightly coupled together, theyform a monolithic “Raft” type foundation for the tower, that has asubstantial overturning resistance capacity attributed to thecombination of its dimensions and its aggregate weight.

Referring again to FIG. 2 it can be appreciated that each of the baseplates 24 of the tower 20 are fastened down to the roof of thefoundation assembly 10 by a tower base anchoring apparatus comprisingfour elongated vertical threaded elements 40, which are known in the artas Anchor Bolts, and are embedded in the shelters' concrete casting. Itwill be appreciated that the resistance capacity of each anchor bolt 40(against pull-out) is greatest when said anchor bolt 40 is sized andlocated such that it is embedded not only in the roof slab of theshelter, but down to a certain depth into the concrete wall of theshelter as well. It is advantageous, therefore, to locate said towerbase anchoring apparatus near the perimeter of the shelter's roof, asclose as possible to the center-plane of an underlying wall. Anillustration of one possible typical shape of anchor bolts 40 can beseen in FIG. 6, and an illustration of the preferred location of towerbase anchoring apparatus 40 relative to the wall underneath can be seenin FIG. 7, which also illustrates that such apparatus 40 embeddedseparately in the castings of two adjacent shelters may be used jointlyto receive the base of a single tower leg.

It will be appreciated by persons skilled in the art that theappropriate mechanical fixing of the tower base to the foundation 10 maybe achieved also by other anchoring apparatus known in the art, such asembedded steel plates or profiles with appropriate holes for bolting.Nevertheless, the use of anchor bolts has the important advantage ofpossible adjustment of the tower's verticality after the completion ofthe foundation's construction. For this reason, the use of anchor bolts40 is selected herein as part of the preferred embodiment of the presentinvention.

In the preferred embodiment illustrated in FIGS. 1 and 2, the tower baseanchoring apparatus is located identically on the roofs of each ofshelters 12, so resultantly the entire tower base anchoring apparatus inthe complete foundation assembly is characterized by a polar symmetryabout said central vertical axis 1, so as to receive tower 20 which, inthe preferred embodiment, is concentric with same central vertical axis1.

It will be appreciated, however, that a foundation constructed accordingto an alternative embodiment of the present invention, or even thefoundation illustrated in FIGS. 1 and 2, may be fitted to receive atower which is eccentric to said central vertical axis 1, i.e. thevertical central axis of the tower may not coincide with said centralvertical axis (of the foundation) 1. This is normally not a desiredarrangement, but rather the result of some constraints, yet it may beachieved either by providing the tower base anchoring apparatus, duringthe casting of the shelters, in an un-symmetrical arrangement, or byusing only part of the tower base anchoring apparatus (if madesymmetrically as illustrated in FIGS. 1 and 2), or even through the useof a tower base interface structure which may have a bottom fixingapparatus of a polar symmetry but a top fixing apparatus fitted to thebase of the eccentric tower.

Following from all the above, it will be appreciated that each offoundation 10 illustrated in FIGS. 1 and 2 and foundation 33 illustratedin FIG. 13 is geometrically best fit to receive a concentric latticetower having four legs, while each of foundation 31 illustrated in FIG.12 and foundation 35 illustrated in FIG. 14 is best fit to receive aconcentric lattice tower having three legs. This, however, is not amandatory rule: a three legged tower may be fitted to be mounted ontofoundation 10 or foundation 33, in a concentric or an eccentric manner,with or without the use of a tower-base interface structure, and thesame applies to the possibility of mounting a four legged tower onto anyof foundations 31 or 35.

The shelters house indoor electronic equipments, and the tower supportsvarious antennae, which are electronically connected to said equipments.The means for said electronic connection can be any kind of feedercables or other antenna cables, which must be routed in between saidantennae and said indoor equipments. One possible way to route saidfeeder cables or antenna cables is to penetrate vertically through theshelter's roof slab. This method, however, contemplates a great hazardof rain-water penetration into the shelter through the cables'penetration detail, in case that detail is not sealed watertight withultimate perfection, and is certainly not the common method. The commonand preferable method is to penetrate into the shelter substantiallyhorizontally, through one of its perimeter walls, which are not abuttingadjacent shelters. Yet the use of an outwardly facing perimeter wall forcable penetration has also several clear disadvantages, the mostimportant of which are the vulnerability of the cables and the greaterlengths of the cable routes.

Hence, it becomes desirable to have an internal vertical shaft, whichwould facilitate a substantially horizontal cable penetration into eachof the shelters (i.e. through a wall) while ensuring minimal routelengths for the cables as well as minimal degree of vulnerability.

Referring again to FIGS. 1 and 2, it can be seen that the four identicalshelters 12 encircle a central vertical shaft 60, which is alsoconcentric with said central vertical axis (of the foundation) 1. InFIG. 4, said central vertical shaft 60 can be seen in a verticalcross-sectional view.

Referring now to FIG. 11, it can be seen that shaft 61 is encircled bythe four different shape shelters 15, 16, 17 and 18, such that shaft 61,in this embodiment, is eccentric relative to the center point of theentire square foundation 11. In FIG. 12, the three identical shelters 32encircle a concentric triangular shaft 62, in FIG. 13, the fouridentical shelters 34 encircle a concentric square shaft 63, and in FIG.14, the six identical shelters 36 encircle concentric hexagonal shaft64.

Nevertheless, the utilization of a central or internal vertical shaft isonly a preferred option, which may be disregarded. FIG. 15 illustrates afoundation assembly 37 made-up by four identical square shelters 38,without any internal shaft. Similarly, FIG. 16 illustrates a foundationassembly 39 of a rectangular contour, made-up by three rectangularshelters of two different types: 238 (two units) and 239, thisembodiment again has no internal shaft. In these last two cases, anddespite the disadvantages described above, cable penetration would takeplace either through the shelters' roofs or through their exteriorwalls.

In order to complete a neat penetration of the antenna cables, as wellas other possible utility cables or pipes, through the walls of theshelters, it would be a good practice to prepare the penetrationopenings in the shelters' casting. These openings may be of any desiredquantity, shapes, sizes and locations, all subject to specificengineering considerations. Most preferably, said openings will befitted to receive certain types of cable penetration sealing devices,available as off-the-shelf purchase items.

Referring now to FIG. 3, cable openings 66 can be seen in the wallsections separating between each of the shelters 12 and the centralshaft 60. Same openings 66 can also be seen in the cross-sectional viewof FIG. 4, in locations which are typical but not mandatory.

Referring now to FIG. 5, there can be seen a preferred embodiment of themeans 70 for coupling together every two adjacent shelters, which areeffected transversely through the shelters' wall sections that abut eachother. In general terms, said means for coupling together every twoadjacent shelters comprise a single or a plurality of substantiallyhorizontal bores, passing substantially transversely through both saidabutting walls, such that substantial bore alignment exists therebetween in the final planned position, as well as a matching number ofsubstantially horizontal elongated connecting members which are insertedthrough said bores and then tightened.

The most simplified embodiment of the means for coupling together everytwo adjacent shelters is shown in FIG. 8, which is a localcross-sectional view made through said means for coupling two adjacentshelters, or more specifically: coupling their two abutting walls 42. Atransverse bore 72 is provided in each of the walls 42, such that theaxes of both bores 72 substantially coincide when the shelters arebrought to their final positions. Then an elongated connecting membercomprising, in this embodiment, a bolt 74 of appropriate size andlength, is inserted through the aligned bores 72, then equipped with amatching nut 75 and tightened. In most practical applications, the useof plate-washers 76, at both ends, is a recommended practice.

FIG. 9 illustrates another embodiment of the means for coupling togethertwo adjacent shelters. In this embodiment, bores 82 in abutting walls 44are made by using lining sleeves 83, which may be of either metal orplastic material, in the concrete casting of said walls 44. In thisembodiment, the elongated connecting member comprises a rod 84, whichmay be threaded all along, or alternatively (as shown) threaded in samedirection only along both its ends. Each end of the elongated connectingmember 84 includes, in this embodiment, a respective end tighteningassembly, comprising two nuts 85 (first nut for tightening and secondnut for locking), as well as preferred plate-washers 86.

It will be appreciated that both the embodiment illustrated in FIG. 8and that illustrated in FIG. 9 may be applicable when the projection ofsaid elongated connecting members from the wall surfaces is tolerable,from the user's point of view, or alternatively, when these inwardlyprojecting elements end up being covered by any type of internal walllining, such as gypsum-board or the like.

Nevertheless, a much more favorable solution is one in which no part ofthe means for coupling together two adjacent shelters would projectinwards from the shelter's wall surface. To make said more favorablesolution feasible, said end tightening assemblies of the elongatedconnecting members must be concealed within large enough recesses in theabutting concrete walls.

FIG. 10 illustrates two slightly different embodiments of said morefavorable solution, which include recesses: on the right hand side ofFIG. 10, recess 90 is formed by metal liner 92 and plate 97, which issubstantially larger than the cross-section of the recess 90. Plate 97includes a central hole which is substantially concentric with bore 88,and allows the passage of elongated connecting member 94 there through.Plate 97 has two roles: first role—to provide a support surface againstwhich the end tightening assembly of said elongated connecting memberabuts when tightened, and second role, owed to its increaseddimensions—to distribute the concentrated load created by tightening theelongated connecting member 94 over a larger area of the concrete wall46.

The left hand side of FIG. 10 illustrates a slightly differentembodiment: in this embodiment recess 91 is no different than recess 90described above, and liner 93 is respectively no different than liner92. However the vertical plate 98 is substantially the size of the crosssection of recess 91. In this embodiment, bent bars 99 which are weldedto liner 93, thereby connected also to plate 98, take the role ofdistributing the concentrated load created by tightening the elongatedconnecting member 94 over a larger area of the concrete wall 47.

Both embodiments illustrated in FIG. 10 indicate the use of liningsleeves 89, which would be welded to the back side of plate 98 (orrespectively plate 97) for the creation of bores 88. Indeed, the use ofa liner for the creation of the recess makes the use of the “linerconcept” throughout the wall's thickness a preferred practice.Nevertheless, it will be appreciated that the use of a liner only overpart of the wall's thickness, for example only to create the recess,while the bore would have no lining sleeve, is also feasible.

Under various service loads, to which the tower and the foundation maybe subjected, shear stresses may develop within the substantiallyvertical surface of contact defined between any two adjacent shelters(surface 50 in the embodiment illustrated in FIGS. 1, 2 and 3). Thepossible consequence of said shear stresses, if they exceed certainresistance values, might be a slight relative vertical or lateralmovement between the respective two adjacent shelters, a veryundesirable consequence that might adversely effect the overallfunctionality of the foundation.

If the faces in contact of any two abutting walls would be totallyplanar surfaces, then the resistance of the system to said relativemovement resulting from shear stresses depends only upon the frictiondeveloped in between said two surfaces in contact, which by itselfdepends upon two factors: the surfaces' friction factor, governed by thematerial and by the surfaces' roughness, and the normal contact pressurethere between, which is governed by the extent of tightening the meansfor coupling the shelters.

It will be appreciated by persons skilled in the art that, in somerealistic loading scenarios, said friction might not provide sufficientresistance to said relative movement resulting from shear stresses, andtherefore said resistance must be increased.

The optional apparatus provided in the present invention, for increasingsaid resistance to relative movement resulting from shear stresses, isthe provision of a bulge or a plurality of bulges, of any desired shapeand size, in said substantially vertical surface of contact definedbetween any two adjacent shelters. In practical terms, each said bulgeis defined by a protrusion formed on one of said two abutting walls, anda socket of a matching shape, size and location, formed in the second ofsaid two abutting walls, the protrusions and sockets are designed so asto interlock with each other, and thereby prevent any possible relativemovement there between.

Referring now to FIG. 5, the embodiment illustrated herein includes, ineach of the four contact surfaces 50, four round conical bulges 52. Inpractical terms, as can bee seen in FIG. 7, each of said bulges 52 isformed by a round conical protrusion 54 on wall 48, and a socket 56 ofmatching shape, size and location, in the abutting wall 49.

It will be appreciated that during the various handling operations thatevery shelter must be subjected to, such as loading for transportation,off-loading on site and bringing to final position with the use of acrane on site, said protrusions may become vulnerable to damage due tomechanical impact. One possible method for protecting said protrusions,and optionally also said sockets, against damages resulting frommechanical impacts is to provide over any desired part of their surfacesliners of material more durable than the concrete, such as steel. Saidliners will be placed, obviously, prior to casting the concrete of therespective walls.

Another possible practical problem may be caused by penetration of ahard foreign particle, such as a small stone, to the space in betweenany two abutting walls during assembly operations on site. Resultantly,when the shelters are pulled as close as possible to each other, throughmaximal tightening of the means for coupling them together, even to adegree that said foreign particle is crushed, it might still prevent thefinal desired contact between the surfaces of said walls, andconsequently said protrusions and matching sockets would not reach fullinterlocking contact, and the benefit of applying said protrusions andsockets would be derogated.

One feasible solution, making the system substantially immune to thepotential problem described above, is designing the abutting wallsurfaces of the shelters geometrically such that, in the process ofassembling any two adjacent shelters, when said protrusions and matchingsockets fully interlock, and resultantly the respective adjacentshelters may not be brought any closer to each other, a relatively thinclearance remains in between the substantially planar parts of the twoabutting wall surfaces. By any mechanical consideration, and as long assaid protrusions cover a certain minimal percentage of the abuttingwall's area, said thin clearances may be left free and the foundationwould nevertheless function properly for the long term. For somenon-structural considerations, however, it would be preferable to fillthe said clearances with cement based grout, or with any other suitablematerial of no structural role, after final tightening of the means forcoupling the shelters.

The precise detailed method of constructing a foundation made inaccordance with the present invention may vary from one specificapplication to the other, a variation that depends, primarily, upon thespecific soil conditions, as well as the specific topographicalconditions existing on site before the commencement of the constructionworks.

For example, if the tower is to be located on a site where a sound rockextends up to the ground surface level, then the load bearing capacityof the natural base in the surface level would not constitute anyproblem, and the only measure that must be applied is the provision of awell-leveled base surface to receive the foundations. This wouldnormally be achieved by flattening the rock surface in the site area tothe best possible extent, and then applying a minimal thickness layer oflean (or normal) concrete, which would be proficiently leveled smooth.The use of a granular base layer instead of the concrete is also anoption, but then additional measures must be taken to reassure that anypart of said granular material might not be washed away by surfacerunning rain water.

If, however, the tower is to be located on normal soil, then the issueof the natural soil's load bearing capacity, as well as other propertiesof said natural soil, in the various depths, must be carefully examined,by a common practice of soil boring and sampling, and analyzed by anexpert, who would establish the recommended measures required to providean adequate load-bearing surface for the foundation at substantially theground surface level.

In the common case, said recommended measures would include theexcavation and removal of a low quality natural top-soil layer, theexact thickness of which would depend on the specific site conditions,and backfilling with an imported, improved quality soil or basematerial, such as gravel, crushed stone or sand. Then, on top of thewell leveled backfilled base the shelters may be directly placed, or ageo-textile sheet may be placed between the two, or by the mostpreferable alternative practice, a thin layer of lean (or normal)concrete may be applied and proficiently leveled smooth to serve as bestquality support surface for placement of the prefabricated shelters.

From this point and on, the method for assembling the foundation wouldbe substantially uniform in all cases: The shelters are placed, with theuse of a sufficient capacity crane, on said prepared base one by one, ina sequential order, so that (with the exception of the first shelter) assoon as each shelter is brought into its final position, relative to thepreceding shelter, it is coupled to said preceding shelter and saidcoupling means are tightened before the assembly process proceeds.Obviously, some of the shelters, in most embodiments the last shelter,must be fitted simultaneously to a plurality of preceding shelters, aswell as be coupled to them all at the same time.

FIG. 22 illustrates the preferred common embodiment of the method forconstructing the foundation embodiment illustrated in FIGS. 1, 2 and 3:

In Step (a) the site area is excavated down to a depth of natural soilwith appropriate load bearing capacity;

-   -   In Step (b) an improved replacement base material of appropriate        quality is backfilled and properly compacted in thin layers;    -   In Step (c) a thin layer of lean (or normal) concrete is cast        and proficiently leveled smooth. In the illustrated embodiment,        a cavity is left in the center of said concrete layer, to allow        free drainage of water from the central vertical shaft.

In Step (d) the first prefabricated shelter is brought to its designatedfinal position;

-   -   In Step (e) the second prefabricated shelter is brought to its        final position relative to the first shelter, and then the means        for coupling these two shelters are applied and well tightened;    -   In Step (f) the third prefabricated shelter is brought to its        final position relative to the second shelter, and then the        means for coupling these two shelters are applied and well        tightened;    -   In Step (g) the fourth and last prefabricated shelter is brought        to its final position relative to both the first and the third        shelters, and then the means for coupling the fourth shelter        with both the first and the third shelters are applied and well        tightened. At this point the foundation construction is        substantially complete, and it is ready to receive the tower        onto it.

Everything described in detailed reference to the drawings up to thispoint relates to the basic foundation assembly, comprising only thecoupled shelters, which is applicable as long as the overturningresistance capacity of said basic assembly is sufficient to stabilizethe tower, considering its height and wind-drag loads.

When a larger tower is required, and consequently a foundation withincreased overturning resistance capacity must be applied in order tosafely stabilize such tower, an additional foundation enhancementassembly would come into use. The foundation enhancement assembly isplaced under said basic assembly of shelters, and it comprises aplurality of prefabricated concrete foundation elements, all havinguniform height, shaped as boxes with open tops, arranged on site withabutting walls and coupled altogether using similar means to those usedto couple the shelters altogether.

Additionally, another set of vertical means of fastening the assembly ofshelters down to the assembly of foundation elements is provided in theshelters' floors and in the foundation elements' tops.

In a preferred embodiment of the foundation enhancement assembly, thefloor of the assembly is projecting horizontally outwards from itsperimeter walls, all around the perimeter or along any part thereof, soas to increase the contact area between the bottom surface of thefoundation and the underlying supporting surface.

FIG. 17 illustrates a preferred embodiment of a foundation enhancementassembly 100, suitable to be used in conjunction with the foundationembodiment illustrated in FIGS. 1 to 3. The assembly comprises fourfoundation elements 102, shaped as rectangular boxes with open tops, andarranged such that each individual foundation element 102 underlies anindividual shelter 12. The foundation elements 102 abut each other, andare coupled altogether using means of transverse coupling 120, which maybe similar to the means 70 used for transverse coupling of the shelters12. It will be noted further that each foundation element 102 has anoutwardly projecting floor slab 112, as described above, as well as acapacity 106 to be filled with any preferred type of soil material, soas to increase the mass of the foundation.

Referring now to FIG. 18, it can be seen that each foundation element102 also includes, in its walls that abut adjacent foundation elements,protrusions 116 as well as recesses 118, which are designed to fulfillthe same role as that of protrusions 54 and matching recesses 56 in thewalls of shelters 12.

Bores 122, forming part of the means of transverse coupling thefoundation elements 120, may also be seen in FIG. 18.

Additionally, on the top surfaces of the walls of foundation element102, there can be seen, in FIG. 18, the vertical inserts 132, which formpart of the means for vertical fastening the shelters 12 down tofoundation elements 102.

The entire means for vertical fastening the shelters 12 down tofoundation elements 102 may be better understood from FIGS. 19, 20 and21.

FIG. 19 illustrates, in a plan view, a typical preferred embodimentshowing the locations of the parts of said means for vertical fastening140, which are embedded near the perimeter of the floor of shelter 12.

FIG. 20 is a cross-sectional view of two abutting walls of shelters 12placed on top of two abutting foundation elements 102 which shows,amongst others, an entire assembled embodiment of said means forvertical fastening the shelters 12 down to foundation elements 102. FIG.21 is an enlargement of said assembled embodiment.

It can be seen, in FIG. 21, that said means for vertical fasteningcomprises an internally threaded metal insert 132, which is a readilyavailable purchase item, available in various sizes, types and brands,commonly in use in the prefabricated concrete industry. Insert 132 isentirely embedded in the wall of foundation element 102, so that it doesnot project at all from said wall's top surface, and is well anchored insaid wall's concrete owing to anchoring element 134 which, in someembodiments, may be a bent steel bar laced through a hole in the bottomof insert 132.

It can be also seen in FIG. 21, that said means for vertical fasteningfurther comprises a vertical bore 144 passing through the floor ofshelter 12. If the user can accept the projection of bolt heads upwardsfrom the shelter's floor, bore 144 may be a simple one, going with auniform cross-section throughout the floor's thickness, either with orwithout a lining sleeve 145.

Yet it is more likely, that such a projection of any fastening elementfrom the shelter's floor may not be acceptable by the users. In thatcase, bores 144 must include recesses 142, which may be similar in shapeand size to recesses 90 or 91 in the walls of shelters 12, or differentthere from, yet the role they fulfill is exactly the same. Comparing theembodiment shown in FIG. 21 to the wall recess embodiments shown in FIG.10, recess liner 143 has the same role as recess liners 92 or 93,horizontal plate 146 has the same role as vertical plate 98 and bentbars 148 have the same role as bent bars 99.

In the embodiment shown in FIG. 21, the vertical fastening member 150 isa normal bolt, sized to match the threads of insert 132, and therequired length. Yet in an alternative embodiment, said verticalfastening member may comprise a threaded rod, with an end tighteningassembly at its top resembling those illustrated in FIG. 10.

It would be clear to any person skilled in the art that theincorporation of the foundation enhancement assembly will also effectsthe method of constructing the foundation. In addition to the need toprepare before hand a greater number of different prefabricatedcomponents, the sequence of construction stages on site is also slightlyeffected.

FIG. 23 illustrates a preferred embodiment of the method forconstructing the foundation enhancement assembly illustrated in FIGS. 17to 21, together with the foundation illustrated in FIGS. 1 to 3:

-   -   In Step (a) the site area is excavated down to a depth        substantially equal to the height of the foundation enhancement        assembly, and in a sufficient area therefore, and the bottom of        the excavation is carefully leveled and compacted;    -   In Step (b) the first prefabricated foundation element is        brought to its designated final position;    -   In Step (c) the second prefabricated foundation element is        brought to its final position relative to the first foundation        element, and then the means for coupling these two foundation        elements are applied and well tightened;    -   In Step (d) the third prefabricated foundation element is        brought to its final position relative to the second foundation        element, and then the means for coupling these two foundation        elements are applied and well tightened;    -   In Step (e) the fourth and last prefabricated foundation element        is brought to its final position relative to both the first and        the third foundation elements, and then the means for coupling        the fourth foundation element with both the first and the third        foundation elements are applied and well tightened;    -   In Step (f) the excavation all around the foundation enhancement        assembly is backfilled and compacted, preferably in relatively        thin layers;    -   In Step (g) the capacities of all the foundation elements, as        well as the cavity encircled thereby, are filled up with a        selected soil material or a granular material;    -   Step (h) represents the same further accomplishment as steps (d)        through (g) in FIG. 22, with the only difference that in this        case special care must be exercised when placing the first        shelter, to the alignment of the vertical means of fastening it        down to the underlying foundation element, so as to ensure that        consequently all following shelters would so align as well.        Additionally, said means for vertical fastening are effected and        tightened in each shelter as soon as it is finally positioned,        and before placement of any further shelters follow.

When step (h) is completed, the foundation is ready to receive therespective tower on its roof.

1. A foundation for a tower, comprising a plurality of prefabricatedconcrete shelters (12, 15, 16, 17, 18), each suitable for housing indoorequipment of a telecom network or the like, said shelters (12, 15, 16,17, 18) being arranged on site such that every shelter is abutting andcoupled to at least one other adjacent shelter, such that asubstantially vertical surface (50) of contact exists there between,across which the means (70, 84, 94) of said coupling is transverselyeffected, resultantly all said shelters (12, 15, 16, 17, 18) aremechanically attached together and function as a monolithic foundation.2. The foundation according to claim 1, wherein the plan view shape ofsaid foundation is substantially a regular geometric shape, which ischaracterized by a polar symmetry about a central vertical axis.
 3. Thefoundation according to claim 2, wherein said shelters (12, 15, 16, 17,18) are all identical and are accordingly arranged around said commoncentral vertical axis of polar symmetry.
 4. The foundation according toclaim 1, wherein each of said shelters (12, 15, 16, 17, 18) includescertain apparatus for anchoring part of tower-base, located on its roof,such that said anchoring apparatus of the entirely assembled foundationis geometrically fit and mechanically adequate to receive the base ofsaid tower (20), either directly or through an interfacing tower-basestructure.
 5. The foundation according to claim 4, wherein saidanchoring apparatus comprises vertical elongated threaded metal elementsof any desired type, known in the art as “Anchor Bolts”, embedded atleast into the concrete roof of said respective shelter, but preferablydown into said roofs supporting concrete wall (48, 49), as well.
 6. Thefoundation according to claim 1, wherein the plan view shapes of saidshelters (12, 15, 16, 17, 18) are such that, when all said shelterscomprising a single foundation are assembled together, they encircle asubstantially vertical internal shaft (60, 61, 62, 63, 64), throughwhich antenna cables and other utility cables or pipes may be routedfrom near the base of said tower (20) into each of said shelters (12,15, 16, 17, 18).
 7. The foundation according to claim 6, wherein anopening (66) or a plurality of openings, of any desired shape or size,for easy and neat routing of said antenna cables and other utilitycables or pipes through the shelter's wall, are provided in desiredlocations in the walls defining said shaft (60, 61, 62, 63, 64), each ofsaid openings preferably being fit to receive any desired type of knownin the art cable-entry sealing systems.
 8. The foundation according toclaim 1, wherein said means of said coupling any two adjacent shelters(12, 15, 16, 17, 18) comprises: A single or plurality of substantiallyhorizontal bores (72), passing substantially transversely through theabutting walls of said two adjacent shelters, such that substantial bore(72) alignment exists when both shelters are finally positioned and areready for being coupled, and A single or plurality of substantiallyhorizontal elongated connecting members (70) passing through said bores.9. The foundation according to claim 8, wherein said substantiallyhorizontal bores (72) include lining sleeves (83).
 10. The foundationaccording to claim 8, wherein said substantially horizontal elongatedconnecting members (70) comprise bolts (74) of appropriate size andlength, each bolt (74) including a respective end tightening assemblycomprising a single nut or a plurality of nuts (75) and, optionally,respective plate-washers.
 11. The foundation according to claim 8,wherein said substantially horizontal elongated connecting members (70)comprise rods, each rod being threaded at both its ends in samedirection, or alternatively threaded throughout its length, andincluding at each of both its ends a respective end tightening assembly,comprising a single nut (85) or a plurality of nuts (85) and,optionally, respective plate-washers (86).
 12. The foundation accordingto claim 10, wherein each, or any selected part, of said substantiallyhorizontal bores (72) includes a recess at its end facing the interiorof the shelter, of any desired shape yet large enough to house saidrespective end tightening assembly of said elongated connecting member,such that in the tightened coupling state, no part of the elongatedconnecting member (94) is projecting inwards from the internal surfaceof the respective wall.
 13. The foundation according to claim 12,wherein said recess (90, 91) is made by a metal liner (92, 93) embeddedin the concrete wall casting, said liner (92, 93) including asubstantially vertical plate (97, 98), at least the size of thecross-section of said recess, with a hole substantially co-axial withsaid bore, said vertical plate being located in the border plane betweensaid recess and said bore, so as to provide a support surface againstwhich said end tightening assembly of said elongated connecting memberabuts when tightened.
 14. The foundation according to claim 13, whereinsaid metal liner (92, 93) of said recess (90, 91) further includesapparatus for distribution of the concentrated load, caused bytightening of said elongated connecting member, over an increased areaof the concrete wall, said apparatus comprising either an enlargement ofsaid vertical plate in excess of the cross-sectional dimensions of saidrecess, or a separate single or plurality of metal plates or bars weldedto the exterior of said metal recess liner.
 15. The foundation accordingto claim 1, wherein said substantially vertical surface (50) of contactbetween any two adjacent shelters (12, 15, 16, 17, 18) comprises asubstantially vertical plane having a bulge (52) or a plurality ofbulges (52), of any desired shape and size, each of said bulges beingdefined by a protrusion formed on one of the two abutting walls (49) ofsaid two adjacent shelters (12, 15, 16, 17, 18), and a socket of amatching shape, size and location formed in the second of said twoabutting walls, all said protrusions (54) and sockets (56) beingprovided so as to interlock with each other and thereby ensure that, inthe assembled and coupled foundation, no relative vertical, lateral orrotational movement may occur in-between any two adjacent shelters inthe foundation assembly.
 16. The foundation according to claim 15,wherein any desired part of the surfaces of said protrusions (54), andoptionally of said sockets as well, is provided with a liner made of amore durable material than the shelter's concrete, so as to ensure thatthe shape of said protrusions (54) and sockets (56) may not be damageddue to any likely mechanical impact during any handling operation of theshelter, such as loading for transportation, off-loading or bringing tofinal position on site.
 17. The foundation according to claim 15,wherein said protrusion/s (54) and said matching socket/s (56) are sizedsuch that, when they fully interlock and resultantly the respectiveadjacent shelters (12, 15, 16, 17, 18) may not be brought any closer toeach other, a relatively thin clearance remains in between thesubstantially planar parts of the two abutting wall surfaces; saidclearance may be left free or alternatively filled with cement basedgrout, or any other suitable material of no structural role, after finaltightening of the means for coupling the shelters (12, 15, 16, 17, 18).18. A method of constructing a foundation for a tower, said methodincluding: Preparing prefabricated components of said foundation,comprising: A plurality of prefabricated concrete shelters, suitable forhousing indoor equipment of a telecom network or the like, shaped suchthat, when arranged on site, every shelter is abutting at least oneother adjacent shelter, with a substantially vertical surface of contactthere between, and provided with certain means for coupling every twoadjacent shelters transversely through said substantially verticalsurface of contact there between, and Sufficient respective number ofelongated connecting members, which are the non-integral parts of saidmeans for coupling every two adjacent shelters; Executing sitepreparation works in designated site area, including: Removal of anyvegetation, including its roots, from the site area, and Leveling andcompacting the designated foundation area to a best feasible degree, soas to form a planar and horizontal support surface, moderately higherthan the surrounding ground level, using for this purpose either soilmaterial naturally available on site (only if found suitable), orimported gravel, crushed stone or sand, or a layer of lean or normalconcrete; Placing said prefabricated concrete shelters in their finaldesignated positions in a sequential order, and effecting and tighteningsaid means of transversely coupling the shelters in the same sequentialorder, such that: When the second of every two adjacent shelters ispositioned, said means for transversely coupling said two shelters areall aligned, and said two shelters cannot be brought any closer to eachother, and Said means for transversely coupling said two shelters beingall finally tightened immediately after positioning said second of thetwo adjacent shelters, and before proceeding with placing any additionalshelters of the foundation, and The last shelter of the foundation, ifabutting more than one adjacent shelter, is brought to is final positionexercising simultaneous alignment with all said adjacent shelters, andsimultaneously effecting and tightening said means of coupling it to allsaid adjacent shelters.
 19. The method according to claim 18, said sitepreparation works further including, as a first step, excavating andremoving a certain thickness of the natural soil underneath thefoundation and in a certain excess area there around, down to a depthwhere the load bearing capacity of the natural soil is found adequate,and backfilling with an improved quality soil or base material such asgravel, crushed stone or sand.
 20. The foundation according to claim 1,further including a foundation enhancement assembly (100), placedunderneath the assembly of said shelters, the two assemblies beingfastened to each other by appropriate means of vertical fastening, saidfoundation enhancement assembly comprising: A plurality of equi-highprefabricated concrete foundation elements (102), each having the shapeof a box open at its top, said foundation elements (102) being arrangedon site such that every foundation element (102) is abutting and coupledto at least one other adjacent foundation element (102), such that asubstantially vertical surface of contact exists there between, acrosswhich the means of said coupling is transversely effected, resultantlyall said foundation elements (102) are mechanically attached togetherand function as a monolithic foundation.
 21. The foundation according toclaim 20, wherein said foundation enhancement assembly further includesan outwardly horizontal projection of its floor (112) from its perimeterwalls, all along its perimeter or along any part thereof, so as toincrease the contact area between the bottom surface of said foundationenhancement assembly and the underlying supporting surface.
 22. Thefoundation according to claim 20, wherein said means of saidtransversely coupling every two adjacent foundation elements (102) issubstantially the same as said means of said transversely coupling everytwo adjacent shelters.
 23. The foundation according to claim 20, whereinsaid substantially vertical surface of contact in-between every twoadjacent foundation elements (102) includes a bulge or a plurality ofbulges, defined by protrusion/s and matching socket/s, having similarproperties and fulfilling the same role as the protrusion/s (116) andmatching socket/s (118) on the abutting surfaces of the walls of saidshelters.
 24. The foundation according to claim 20, wherein saidappropriate means for vertical fastening of said assembly of shelters(12, 15, 16, 17, 18) down to said assembly of foundation elements (102)comprises: A plurality of internally threaded metal devices, known inthe art as “prefabricated concrete inserts”, embedded vertically in thetop surfaces of the walls of said foundation elements (102), and Aplurality of vertical bores (144) in the floor of each shelter, locatedso as to be aligned, in the final positioning, with and above saidinternally threaded devices, and A plurality of elongated verticalfastening members, each having a threaded bottom portion matching thethread of said internally threaded devices, sized so as to be insertedinto one of said vertical bores and thereby secure the floor of arespective shelter down to the top of a wall of an underlying foundationelement.
 25. The foundation according to claim 24, wherein saidelongated vertical fastening members (150) comprise bolts of appropriatesize and length and, optionally, a respective plate-washer.
 26. Thefoundation according to claim 24, wherein said elongated verticalfastening members (150) comprise rods, each rod being threaded at bothits ends in same direction, or alternatively threaded throughout itslength, and including at its top end, a respective end tighteningassembly, comprising a single nut or a plurality of nuts and,optionally, a respective plate-washer.
 27. The foundation according toclaim 24, wherein each, or any selected part, of said vertical bores(144) in the shelters' (12) floors includes a recess at its top end,having same shape and size as the recesses in the ends of saidsubstantially horizontal bores (122) in the shelters' walls, or anydifferent desired shape or size, fulfilling the same role as that ofsaid recesses (142) in the ends of said substantially horizontal boresin the shelters' walls, and made according to any preferred embodimentthereof.
 28. The method according to claim 18, the preparedprefabricated components further comprising: A plurality of equi-highprefabricated concrete foundation elements, shaped as boxes open attheir tops and such that, when arranged on site, every foundationelement is abutting at least one other adjacent foundation element, witha substantially vertical surface of contact there between, and providedwith certain means for coupling every two adjacent foundation elementstransversely through said substantially vertical surface of contactthere between, and further provided with other means of verticalfastening between said shelters and said foundation elements, and Asufficient respective number of elongated connecting members, which arethe non-integral parts of said means for coupling every two adjacentfoundation elements, and A sufficient respective number of elongatedvertical fastening members, which are the non-integral parts of saidmeans for vertical fastening between said shelters and said foundationelements; and The site preparation works further including, as a firststep, excavating the designated foundation area to a depth substantiallyequal to the height of each of said foundation elements, at which depthsaid leveling and compacting the designated foundation area isperformed; and Placing of said prefabricated concrete shelters ispreceded by: Placing all said foundation elements in a sequential orderand coupling them altogether in the same method as described for placingsaid shelters, and Backfilling the excavation around the placed andcoupled foundation elements, preferably in individual layers such thatappropriate compaction is applied to each layer before the material offollowing layer is backfilled, and Filling up the entire capacity withineach of said foundation elements, as well as (if applicable) of thecavity encircled thereby, with local soil or with imported soil orgranular material or sand.
 29. The method according to claim 28, saidsite preparation works further including, as a second step, excavatingand removing a certain additional thickness of the natural soilunderneath the foundation and in a certain excess area there around,down to a depth where the load bearing capacity of the natural soil isfound adequate, and backfilling up to a depth designated as the baselevel of said foundation elements with an improved quality soil or basematerial such as gravel, crushed stone or sand.